1. Field of the Invention
The invention relates to a method for the thermal regeneration of charged adsorption materials by means of a gaseous regeneration medium.
2. Description of the Prior Art
Various adsorption materials as for example, activated carbon, activated clay, and molecular filters are used for gas- and liquid purification, and thereby become charged with the adsorbed impurities. These charged adsorption materials can be thermally regenerated. For this purpose a gaseous regeneration medium is heated, and conducted through the adsorption material. Water vapor or gases which are inert with respect to the adsorption materials and their impurities, and often have a low oxygen content are frequently used as the regeneration medium. The regeneration medium leaving the adsorption material layer contains the expelled impurities in vapor form. These substances, mostly of organic nature, can be separated from the regeneration medium by cooling and condensation. With water vapor as the regeneration medium, these substances together with the water are condensed at the cooling, and the separation of the condensate from the water is performed thereafter.
Considered from an energy point of view, by heating the regeneration medium, energy is put into the system in the order of magnitude of the adsorption heat for effecting the desorption, while at cooling, the condensation heat is liberated which together with the sensible heat of the desorption medium is given off to the environment through the cooling media of air or water. Thereby, water-vapor regeneration operates especially disadvantageously, because here the large condensation heat of the water vapor is lost.
According to the German Published Non-Prosecuted Application OS 26 31 255, it is proposed as an improvement with respect to energy in regeneration with water vapor, to use a part of the condensation heat of the regeneration steam for producing fresh regeneration vapor. In spite of some improvement, the energy consumption remains high, as can be learned from the examples given there: Per kilogram of desorbed and condensed impurities, 2.5 kg, respectively, 4.6 kg water vapor are required. Though this is only 1/3 of the conventional amount of water vapor, its condensation heat is lost in addition to the condensation heat of the impurities.
German Patent No. 704,350 describes a method wherein a gaseous desorption medium is conducted in a desorption circuit by a blower, heated in a heater E, and then passed in contact with the used-up adsorption material in the adsorber to renew it. The expelled desorbate is deposited by cooling in a condenser which serves as "desorbate catcher". In order not to lose the total heat contained in the gaseous desorption medium, it is proposed in the patent that this condenser be not passed through by the flow of the gaseous desorption medium, but that the partial pressure of the desorbate be lowered by cooling it in a space which is connected with the desorption circuit, but not passed through by the flow, and thus create a partial pressure, in which the desorbate diffuses for cooling without the gaseous desorption medium losing the sensible heat contained in it. Thereby, the expected saving in heating energy can only occur at the end of the desorption, i.e. when the adsorption layer is fully heated. But since the adsorption material must be cooled after the desorption is finished, the saving of heating energy cannot include the sensible heat stored in the adsorption material.